Extreme pressure lubricant



United States Patent EXTREME PRESSURE LUBRICANT Samuel J. Sokol, deceased, late of Beacon, N. Y., by Harry Sokol, administrator, Brooklyn, and William J. Coppoc, Beacon, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application September 26, 1950, Serial No. 186,918

7 Claims. (Cl. 25237.2)

This invention relates to an extreme pressure lubricant, and more particularly to a lead naphthenate gear lubricant adapted for heavy duty service.

One of the principal objects of the present invention is to provide a lead naphthenate gear lubricant of this type which meets the rigorous requirements of U. S. Army Specification 2-105B for heavy duty automotive gear lubricants; which is now designated as MIL-L-2105.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the appended claims.

With the increasing speeds and torques provided by modern automotive equipment, resulting in increased bearing pressures or other rigorous service conditions on the gear teeth of hypoid gears or other instances of metal to metal contact in heavy duty service, the extreme pressure requirements for lubricants of this character have steadily risen to the point where previously known lubricants of this type no longer were suitable in meeting the heavy duty requirements. These increased service requirements have culminated in the adoption of U. S. Army Specification 2-105B (now designated as MIL-L- 2105) which has extremely rigorous requirements as represented particularly by a High Speed Axle Test AXS- 1569 and a High Torque Axle Test AXS-1570. So far as is known, only one lead soap gear lubricant has heretofore satisfactorily met the requirements of this specification, which run the gamut from high speed at relatively lower pressure to extremely high pressure at a lower speed.

In accordance with the present invention, an extreme pressure lubricant of superior quality which meets the foregoing specification is provided by compounding with a mineral lubricating oil as the predominating or major constituent, a substantial proportion of lead naphthenate together with a combination of three different types of sulfur and chlorine-containing additives represented by (l) a sulfo-chlorinated sperm oil, (2) a chlorinated paraffin wax, and (3) a sulfurized sperm oil composition selected from the group consisting of a sulfurized mixture of mainly sperm oil and lanolin and sulfurized sperm oil. The proportions of the said three sulfur and chlorinecontainingadditives as well as the lead naphthenate have been found critical in satisfactorily meeting both the high speed and high torque axle tests. The formulation in accordance with the present invention thus consists essentially of a mineral lubricating oil as the predominating constituent blended with the following additives in percent by weight based on the lubricant:

Percent by weight Lead naphthenate 8-1 Sulfo-chlorinated sperm oil 8-12 Chlorinated paraflin wax 2.5-3.5 Sulfurized sperm oil composition 4-7.5

The mineral lubricating oil, which ordinarily constitutes about 60-78% by weight of the lubricant, is preferably a blend of a residual lubricating oil with a distillate lubricating oil to meet the desired viscosity for the particular grade of automotive gear lubricant. A preferred type of mineral lubricating oil is one from a mixed base crude which is relatively low in wax content and thus has characteristics of a naphthene base crude, but at the same time has a relatively high viscosity index and thus has characteristics of a paraffin base crude. A very satisfactory crude of this character is represented by the so-called Manvel crude. The blend of the residual oil ICC from this crude with a distillate oil from the said crude results in improved color, stability and low temperature performance in addition to providing proper viscosity ranges for the various grades of automotive gear lubricants. In adjusting the viscosity for the various grades, the proportion of residual oil is increased while the distillate oil is concomitantly decreased as the viscosity and grade of the lubricant is raised, the proportions of the extreme pressure additives compounded therewith remaining essentially constant.

The lead naphthenate utilized in the lubricant can be prepared from naphthenic acids obtained in the refining of petroleum, particularly the naphthenic acids derived from lubricating oil fractions. Moreover, the naphthenic acids can contain some non-saponifiable mineral oil which may vary up to 30% or more. A typical lead naphthenate, prepared from lubricating oil naphthenic acids having a non-saponifiable content of about 23%, has a PhD content of roughly about 20% by weight. In the following description and claims, where lead naphthenate is specified, it will be understood that this refers to a product of this type having a PbO content of about 20%, unless the contrary appears from the text. Lead naphthenate prepared from naphthenic acids essentially freed from non-saponifiable content will run about 30% PbO content. In calculating the percentage of lead naphthenate of the higher PbO content to be employed in accordance with the proportion ranges set forth herein, which are based on the lead naphthenate of approximately 20% PbO content, it will be understood that the proportion is decreased in accordance with the ratio of the higher PbO content to the 20% PhD content to provide an equivalent PbO content in the finished lubricant.

The sulfo-chlorinated sperm oil employed in the present lubricant may be produced by reacting the sperm oil with about 10-15% sulfur monochloride without added heat, followed by subsequent stabilization of the reaction product by heat treatment at temperatures of about 300-350 F., followed by neutralization of any strong acidity so that the product passes the copper strip corrosion test by passing the treated oil in contact with marble chips. Or the sperm oil may be first chlorinated as by bubbling chlorine gas through the material at F., and the resulting chlorinated product subsequently treated with about 10-15% of sulfur monochloride and stabilized in the foregoing manner. A preferred compound of this type for purposes of the present invention is a sulfo-chlorinated sperm oil containing about 4-6% of combined sulfur and about 4-6% of combined chlorine. A commercially available product of this character is Sulchlor 55 sold by Carlisle Chemical Works Inc. which is a sulfurized and chlorinated sperm oil containing roughly about 5% each of combined sulfur and chlorine.

The chlorinated paraffin wax employed in the present lubricant is one having a high content of combined chlorine, the major proportion of which is in a so-called active state. For example, a preferred material of this character has a total combined chlorine content of about 40-45% with an active chlorine content of about 29- 34%. A commercially available product of this character is sold under the name of Anglamol 40 by Lubrizol Corp. Preferably, the chlorinated paraffin wax contains a small proportion of an oil-soluble corrosion inhibitor of the type disclosed in U. S. Patent No. 2,298,- 638, which functions to neutralize the effect of any decomposition of the chlorinated parafiin wax with the release of free chlorine. Anglamol 40 contains a small amount of phenoxy propylene oxide as a corrosion inhibitor of this type.

The sulfurized sperm oil composition employed in the present lubricant may be prepared by sulfurizing either sperm oil, or a mixture of mainly sperm oil and lanolin, with about 8-15% of sulfur at 350-400 F. for about l-3 hours. The resulting sulfurized product contains about 713% of combined sulfur in a form which renders the product non-corrosive in the copper strip corrosion test and yet is sufficiently active to provide the reis responsible for the extreme pressure properties thereof. A commercially available product of this type is sold under the name of S/V 28 Base by Socony Vacuum Oil Company, and is a sulfurized mixture of mainly sperm oil with a small amount of lanolin, the principal constituent being a sulfurized derivative of cetyl oleate. Typical tests on this product are the following:

Gravity, API 14.5-16.0 SUS viscosity at 210 F 190-230 Sulfur, weight percent 9-11 Sap. No. 140-155 In addition to the foregoing ingredients, a small proportion of an anti-foam agent is preferably incorporated in the lubricant. A very satisfactory material of this type is a silicone polymer, such as dialkyl, diaryl or alkyl-aryl silicone polymer of known anti-foam properties. A typical material of this type is dimethyl silicone polymer having a kinematic viscosity at 25 C. of about 1001000 centistokes. The silicone polymer is conveniently handled as a concentrate in a hydrocarbon solvent such as kerosene. In the specific examples listed hereinbelow, the concentrate was prepared by dissolving dimethyl silicone polymer in kerosene in proportion of 10 grams of the polymer with suificient kerosene to make up to a volume of 100 ccs. The anti-foam agent, such as the silicone polymer concentrate, is employed in the lubricant in a proportion of about 0.00l0.015% by weight, preferably about 50 parts per million.

In addition to the foregoing ingredients, the extreme pressure lubricant may also contain a small proportion of the order of about 0.13%, and preferably about 0.5- 1.0%, by weight of an aliphatic dihydric or trihydric alcohol, such as glycerine, to increase the Timken test of the lubricant, as disclosed and claimed in the copending application of Theodore W. Langer, Serial No. 175,- 482, filed July 22, 1950, now abandoned. Where the purpose is to meet the 2-105B specification and extremely high Timken value is not required, it will be understood that the present invention comprehends the omission of the polyhydric alcohol and the attainment of the required extreme pressure properties which satisfy the high speed and high torque tests by a combination in proper proportions of the three sulfur and chlorine-containing additives in conjunction With lead naphthenate in the mineral lubricating oil. It will be understood that the extreme pressure lubricant may also include small proportions of known and anti-corrosive agents, pour depressants, viscosity index irnprovers, oxidation inhibitors, dyes and the like, which do not deleteriously affect the essential properties of the lubricant as specified above.

In order to illustrate the critical nature of the proportions of the foregoing essential ingredients in meet ing the 2-105B specification, the following Table I sets forth the results obtained with five different formulations of similar character, but differing mainly in proportions of the ingredients, in the essential tests prescribed by the 2-105B specification:

Parafiin base residual lubricating Mcthacrylate ester polymer Anti-foam concentrate, p. p. m. 50 50 5 50 50 U. S. Army 2-105B Tests:

High Speed Axle (AXS-l569).. Fail Pass Pass Fail Pass High Torque Axle (AXS-1570). Pass Fail Fail Pass Pass Moisture Axle Corrosion (AX S-1571) Pass Pass Pass Pass Pass Storage S0111 y (AXS- 1572) Fail Pass Pass Pass Compatibility (AXE-1572 Mod. Fail Pass Pass Pass Foam (AXS-1562) Pass Pass Pass Pass The most diflicult tests of the 2-105B specification to 1569) and the High Torque Axle Test (AXS1570). Since these are standard tests on which specifications are published further description thereof is not given except to point out that the former test evaluates the inbricating effect of the test lubricant on a pinion and hypoid gear set under conditions simulating automotive high axle speed at lighter load; whereas the latter test evaluates the lubricant under conditions simulating high torque at comparatively lower speeds. The success or failure of the test in each case is judged by the appearance of the gears at the termination of the test, as to whether there is any evidence of scoring, rippling, ridging, pitting or serious discoloration of the gears. In addition, the 2-105B specification includes a so-called Moisture Axle Corrosion Test (AXS-157l) wherein gears must show no sign of corrosion from the lubricant during the test; a Storage Solubility Test (AXS-1S72) wherein the lubricant on storage for the required period must be stable so as to have not more than 0.25% by weight of solid separation and 0.5% by volume of liquid separation; and a Compatibility Test (AXS1572 modified) wherein the requirements are the same as specified in the storage solubility test and also the lubricant must show no evidence of sludge on heating; and a Foam Test (AXS-1562) wherein the test lubricant must develop not more than 650 mls. of foam during five minutes of aeration.

As will be noted from the foregoing table, composition 1 which was formed from a parafiin base residual-distillate blend and contained the combination of the sulfochlorinated sperm oil and the chlorinated paraffin wax in addition to lead naphthenate within the effective proportion range, but contained no sulfurized sperm oil, failed the high speed axle test as well as the storage solubility and compatibility tests of the 2-105B specifica tion. Composition 2 which was formed from the preferred mixed base residual-distillate blend and contained all of the essential additives of the present invention but with both the lead naphthenate and the sulfo-chlorinated sperm oil in proportions just below the critical lower limits, failed the high torque axle test. This shows that the sulfurized sperm oil in proper proportions is essential to the passage of the high speed test, while both the lead naphthenate and the sulfo-chlorinated sperm oil in proper proportions are essential to passage of the high torque test. Composition 3 which had the same additive content as composition 2 but was formed from a parafiin base residual-distillate blend, also failed the high torque axle test. The storage solubility and compatibility tests were not run on this blend. Composition 4, formed from the preferred mixed base residual-distillate blend and containing the higher proportions of lead naphthenate and sulfo-chlorinated sperm oil in addition to the proper proportion of sulfurized sperm oil, but wherein the chlorinated paraifin wax was lowered to a proportion below the critical minimum, failed the high speed test. This shows that the chlorinated paraiiin wax in proper proportion is also essential to passage of the high speed test, and demonstrates that the combination of the said essential additives in the proper proportions are required in the single composition to pass both the high speed and high torque tests. This is proved by composition 5 which contained all of the essential additives within the critical proportion range therefor, and which satisfactorily passed all the tests of the 2-105B specification.

The following preparation of a commercial batch of the heavy duty automotive gear lubricant of composition 5 of the foregoing Table I is given by way of example. The ingredients employed for a 1,000 pound batch of the gear lubricant are as follows:

Typical tests obtained on the foregoing ingredients were:

Mixed base residual lubricating oil:

Gravity, API 17.1 Flash, C. O. C., F 650 Vis., SSU, at 210 F 754 Vis., Saybolt Furol, at 122 F 1,739 Pour, F 55 Carbon residue, percent 7.1 Ash, percent 0.03 Mixed base distillate lubricating oil:

Gravity, API 25.3 Flash, C. O. C., F 335 Vis., SSU, at 100 F 108.7 Pour, F -40 Lead naphthenate:

Lead oxide, percent 19.5 Unsaponifiable, percent 23.1 Sulchlor 55:

Chlorine, percent 5.17 Sulfur, percent 5.67 Anglamol 40:

Chlorine, percent 43.4 Active chlorine, percent 29.1 Sulfurized sperm oil:

Gravity, API 15.2 Vis., SSU, at 210 F 217 Total sulfur, percent 9.48 Sap. No 150.8

The residual and distillate mineral lubricating oils were charged to a large steam-heated kettle provided with water cooling and a stirrer. The oil blend was heated to 175 F. with vigorous stirring, and then the lead naphthenate was added and the temperature maintained for /2. hour while stirring was continued. The oil solution was then cooled with stirring to 150 F. While the above operations were being carried out in the large kettle, a blend of the listed quantities of Sulchlor 55, Anglamol 40, sulfurized sperm oil, glycerine and the anti-foam concentrate was prepared in a small mixing kettle by charging the ingredients, heating to 150 F. with stirring, and holding the mixture at that temperature until the contents of the large kettle had cooled to 150 F. The contents of the small kettle were then added to the oil solution in the large kettle, the small kettle being rinsed by recirculating the lubricant through it. The resulting compounded oil was then stirred vigorously for one hour in the large kettle at 150 F., and it was then pumped into containers or cans.

Typical tests obtained on the finished gear lubricant in addition to those listed above in Table I, were as follows:

Gravity, API 16.0 Flash, C. O. C. F 390 Vis., SSU, at 100 F 1100 Vis., SSU, at 210 F 90.4 V. I 90 Total sulfur, percent 1.27 Chlorine, percent 1.76 Lead, percent 1.99

The foregoing gear lubricant was of the so-called 90 grade, meaning that its SSU viscosity at 210 F. is about 90. In order to produce a lubricant of a different grade, the proportions of the residual and distillate lubricating oils are altered, while the proportions of the additives remain the same. Thus, in the preparation of the 80 grade, about 13% of the residual oil is employed in conjunction with 58.5% of the distillate oil; whereas in the production of the 140 grade, 43% of the residual oil is employed with 28.5% of the distillate oil.

By way of example, when utilizing a different lead naphthenate containing a PbO content of about 30%, the composition duplicating the lead soap extreme pressure lubricant of composition 5 of Table I was prepared with the following ingredients:

Mixed base residual lubricating oil..weight percent" 31.4

For the 80 grade of the lubricant utilizing the lead naphthenate of about 30% PbO content, the residual oil content is 13.6% by weight and the distillate oil content is 61.2% by weight; while for the grade, the residual oil content is 45% and the distillate oil 29.8%, the percentages of the additives remaining the same in each case. It is thus seen that the different grades of lead naphthenate are employed in proportions to give an equivalent PbO content in the finished lubricant. As noted above, the proportion range for lead naphthenate set forth in the following claims is based upon a product having a PbO content of roughly 20% by weight.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. An extreme pressure liquid lubricant suitable as an automotive gear lubricant for heavy duty service, consisting essentially of a mineral lubricating oil as the predominating constituent blended with the following additives in per cent by weight based on the lubricant:

Lead naphthenate as the sole metal soap 8-12 Sulfo-chlorinated sperm oil 8-12 Chlorinated paraffin wax 2.5-3.5 Sulfurized sperm oil composition selected from the group consisting of a sulfurized mixture of mainly sperm oil and lanolin, and sulfurized sperm oil 4-7.5

2. An extreme pressure liquid lubricant suitable as an automotive gear lubricant consisting essentially of the following constituents in per cent by weight based on the lubricant:

Blend of residual and distillate mineral lubricat- 3. An extreme pressure liquid lubricant suitable as an automotive gear lubricant consisting essentially of the following constituents in the approximate per cent by weight based on the lubricant: Mixed base residual lubricating oil 13-43 Mixed base distillate lubricating oil 59-28 Lead naphthenate as the sole metal soap 10 Sulfo-chlorinated sperm oil (4-6% combined S and 4-6% combined Cl) 10 Chlorinated paraffin wax (29-34% active Cl and 40-45% total Cl) 3 Sulfurized sperm oil composition (7-l3% combined S) selected from the group consisting of a sulfurized mixture of mainly sperm oil and lanolin, and sulfurized sperm oil 5 4. An extreme pressure liquid lubricant suitable as an automotive gear lubricant consisting essentially of the following constituents in the approximate per cent by weight based on the lubricant:

Mixed base residual lubricating oil Lead naphthenate as the sole metal soap Mixed base distillate lubricating oil 59-28 Sulfo-chlorinated sperm oil (4-6% combined S and 4-6% combined Cl) Chlorinated paraffin wax (29-34% active Cl and 40-45% total Cl) 3 Sulfurized sperm oil composition (7-13% combined S) selected from the group consisting of a sulfurized mixture of mainly sperm oil and lanolin, and sulfurized sperm oil 5 Glycerine 0.5

5. An extreme pressure liquid lubricant according to claim 1, also containing 0.1-3.0% by weight based on the lubricant of glycerine.

6. An extreme pressure liquid lubricant according to claim 1, also containing 0.001 to 0.015 weight per cent dimethyl silicone polymer concentrate formed by dissolving said polymer in kerosine in a portion of 10 g. of polymer with sufiicient kerosine to make up to a volume of 100 cc.

7. An extreme pressure liquid lubricant according to claim 1, also containing 0.1 to 3.0 weight per cent of glycerine and 0.001 to 0.015 weight per cent dimethyl silicone polymer concentrate formed by dissolving said polymer in kerosine in a portion of 10 g. of polymer with sufiicient kerosinc to make up to a volume of 100 cc.

References Cited in the file of this patent UNITED STATES PATENTS Miller Nov. 15, Prutton et a1 July 16, Lincoln et a1 Dec. 2, McNulty et al. J an. 9, Zimmer J an. 4, Yule Feb. 12, Folda May 30,

Schiermeier Aug. 1, 

1. AN EXTREME PRESSURE LIQUID LUBRICANT SUITABLE AS AN AUTOMOTIVE GEAR LUBRICANT FOR HEAVY DUTY SERVICE, CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL AS THE PREDOMINATING CONSTITUENT BLENDED WITH THE FOLLOWING ADDITIVES IN PER CENT BY WEIGHT BASED ON THE LUBRICANT: LEAD NAPHTHENATE AS THE SOLE METAL SOAP ------8-12 SULFO-CHLORINATED SPERM OIL ---------------- 8-12 CHLORINATED PARAFFIN WAX ------------------- 2.5-3.5 SULFURIZED SPERM OIL COMPOSITION SELECTED FROM THE GROUP CONSISTING OF A SULFURIZED MIXTURE OF MAINLY SPERM OIL AND LANOLIN, AND SULFURIZED SPERM OIL ---------------------- 4-7.5 